Re: [PATCH v4 7/9] IB/core: generic RDMA READ/WRITE API

[Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>]

On Fri, Mar 11, 2016 at 02:39:16PM -0800, Bart Van Assche wrote:
> The above is fine with me. But when I ran a test with rdma_rw_use_mr() 
> changed into "return true" the following error messages appeared in the 
> kernel log:
>
> [  364.460709] ib_srpt 0x1: parsing SRP descriptor table failed.
> [  383.604809] ib_srpt 0x0: parsing SRP descriptor table failed.
> [  383.605627] ib_srpt 0x2: parsing SRP descriptor table failed.
> [  386.702905] ib_srpt 0x3: parsing SRP descriptor table failed.
> [  386.703092] ib_srpt 0x4: parsing SRP descriptor table failed.
> [  386.703242] ib_srpt 0x5: parsing SRP descriptor table failed.
> [  386.703411] ib_srpt 0x6: parsing SRP descriptor table failed.
>
> Is this expected? I ran this test on a server equipped with two mlx4 HCAs 
> with latest firmware (2.36.5000). I installed git commit 
> c4c65482b56a433a82bc5b63db8ba125727e9f80 of the rdma-rw-api merged with 
> v4.5-rc7. Initiator and target drivers were running on the same server and 
> were communicating with each other via loopback. Before I modified 
> rdma_rw_use_mr() the same test passed on the same setup.

I think this might be the case when SRP gets multiple SGL entries.
In this case the number of MRs allocated is limited and srpt should
handle rdma_rw_ctx_init failures due to the lack of MRs.  If you add
the ib_mr_pool_get failure printk back that you asked me to remove
I bet it's going to trigger.
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